I have a couple of LG 34CB88-P monitors and I am struggling to get FreeSync to work on them. I just purchased a Radeon RX Vega 64 and installed the latest Radeon 17.11.1 drivers that were available for Win 10 64 bit. The monitors are hooked up via DisplayPort using the provided LG cables (though I have also tried a couple of DP 1.2+ compatible cables not provided by the manufacturer, as well) and I have installed the driver for the monitors. In the internal monitor settings I have made sure that FreeSync is enabled.

When I view the Display tab in the Radeon settings it says FreeSync is "Not Supported" and there is no option to enable it. I also have the LG on screen display software installed and in the monitor settings within here it explicitly says FreeSync is "On". I thought perhaps it might actually be enabled and the Radeon software might be incorrectly reporting its status, but there is still clearly visible screen tearing in its current state.

I'm assuming this is a Radeon driver issue, but is there anything else I can try to properly enable FreeSync? Really it is the deciding factor as to why I purchased AMD this go around because I wanted active sync and didn't want to pay extra for that overpriced NVidia G-sync crap.

Wow, never would have thought that was the problem, but you're correct. The manual explicitly says it supports FreeSync in the range of 55-75 Hz, but setting it explicitly to 75 Hz automagically enabled it.